1) in a general sense, to screw over people of a particular background.
2) to fuck everything up and ruin things for everybody involved, including themselves.
3) to cast shame on a group of people for past wrongdoing as reason to engage in widespread ethnic masochism.

Upon returning from the optometrist, Lydia excused herself to the restroom to make a movement. George, feeling giddy, joined her in the bathroom, got down on all fours, and gave her the merkeling of a lifetime.